Camera systems including multiple cameras are used to image a common scene from different vantage points. The images captured by such camera systems may be combined to provide information not obtainable from any individual camera included in the camera system. Some applications are focused on capturing video at frame rates significantly in excess of the frame rate associated with a single camera, which is useful for capturing video of fast moving objects. In other applications, cameras of different types are used to obtain different types of information. For instance, a camera system may include one camera for capture of color images and another camera to capture of monochrome images. Camera systems including multiple cameras have proven particularly useful in stereo camera applications.
Stereo cameras consist of two or more camera systems spatially offset from each other. Each camera captures an image of the same scene and subsequent analysis of the recorded images provides distance information in addition to standard two-dimensional images. The configuration mimics that of a pair of eyes. Humans perceive distance by comparing visual information taken in through the eyes. The distance between the eyes results in slight differences in the images formed in the two eyes. The brain processes this disparity to determine the distance to various objects in the scene and provide depth perception. Similarly, two cameras placed next to each other and viewing the same scene will capture slightly different images due to the distance between the two cameras. Objects from the scene will appear in slightly different positions in the images. If the cameras are spaced apart from each other by a known distance, the three-dimensional location of objects in the scene relative to the stereo camera can be determined from the captured images by triangulation.
Stereo cameras are being found in an increasing number of applications requiring image capture and distance information for objects in the scene. For example, stereo cameras are being implemented in cars to help prevent accidents by monitoring the surroundings and determining if the car is getting too close to other objects or people. In addition to location and distance information, stereo cameras can provide the actual size of objects by applying the determined distance between the object and the stereo camera to the size of the object, as measured in the image. This feature is useful in applications requiring object recognition, such as surveillance, machine vision, and robotic equipment. Some stereo cameras include an additional camera that provides a color image of the scene viewed by the stereo camera.